The half-life for the radioactive decay of C-14 is 5715 years and is independent of the initial concentration. How long does it take for 25.00% of the C-14 atoms in a sample of C-14 to decay? If a sample of C-14 initially contains 1.20 mmol of C-14, how many millimoles are left after 2725 years?
a) 5715 years, 0.6 mmol
b) 2860 years, 0.6 mmol
c) 5715 years, 1.2 mmol
d) 2860 years, 1.2 mmol